Cable-type secondary battery

ABSTRACT

The present invention relates to a cable-type secondary battery having a horizontal cross section of a predetermined shape and extending longitudinally, comprising: a core for supplying lithium ions, which comprises an electrolyte; an inner electrode, comprising an open-structured inner current collector surrounding the outer surface of the core for supplying lithium ions, an inner electrode active material layer formed on the surface of the inner current collector, and an electrolyte-absorbing layer formed on the outer surface of the inner electrode active material layer; a separation layer surrounding the outer surface of the inner electrode to prevent a short circuit between electrodes; and an outer electrode surrounding the outer surface of the separation layer and comprising an outer electrode active material layer and an outer current collector.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Application No.PCT/KR2012/008397 filed on Oct. 15, 2012, which claims priority under 35USC 119(a) to Korean Patent Application No. 10-2011-0104873 filed in theRepublic of Korea on Oct. 13, 2011 and Korean Patent Application No.10-2012-0114104 filed in the Republic of Korea on Oct. 15, 2012, thedisclosures of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a cable-type secondary battery, whichcan freely change in shape, and more particularly to a cable-typesecondary battery having a core for supplying lithium ions.

BACKGROUND ART

Secondary batteries are devices capable of storing energy in chemicalform and of converting into electrical energy to generate electricitywhen needed. The secondary batteries are also referred to asrechargeable batteries because they can be recharged repeatedly. Commonsecondary batteries include lead accumulators, NiCd batteries, NiMHaccumulators, Li-ion batteries, Li-ion polymer batteries, and the like.When compared with disposable primary batteries, not only are thesecondary batteries more economically efficient, they are also moreenvironmentally friendly.

Secondary batteries are currently used in applications requiring lowelectric power, for example, equipment to start vehicles, mobiledevices, tools, uninterruptible power supplies, and the like. Recently,as the development of wireless communication technologies has beenleading to the popularization of mobile devices and even to themobilization of many kinds of conventional devices, the demand forsecondary batteries has been dramatically increasing. Secondarybatteries are also used in environmentally friendly next-generationvehicles such as hybrid vehicles and electric vehicles to reduce thecosts and weight and to increase the service life of the vehicles.

Generally, secondary batteries have a cylindrical, prismatic, or pouchshape. This is associated with a fabrication process of the secondarybatteries in which an electrode assembly composed of an anode, acathode, and a separator is mounted in a cylindrical or prismatic metalcasing or a pouch-shaped casing of an aluminum laminate sheet, and inwhich the casing is filled with electrolyte. Because a predeterminedmounting space for the electrode assembly is necessary in this process,the cylindrical, prismatic or pouch shape of the secondary batteries isa limitation in developing various shapes of mobile devices.Accordingly, there is a need for secondary batteries of a new structurethat are easily adaptable in shape.

To fulfill this need, suggestions have been made to develop linearbatteries having a very high ratio of length to cross-sectionaldiameter. Korean Patent Application publication No. 2005-99903 disclosesa flexible battery consisting of an inner electrode, an outer electrodeand an electrolyte layer interposed therebetween. However, such batteryhas poor flexibility. The linear batteries use a polymer electrolyte toform an electrolyte layer, but this causes difficulties in the inflow ofthe electrolyte into an electrode active material, thereby increasingthe resistance of the batteries and deteriorating the capacity and cyclecharacteristics thereof.

DISCLOSURE Technical Problem

The present invention is designed to solve the problems of the priorart, and therefore it is an object of the present invention to provide asecondary battery having a new linear structure, which can easily changein shape, maintain excellent stability and performances as a secondarybattery, and facilitate the inflow of an electrolyte into an electrodeactive material.

Technical Solution

In order to achieve the objects, the present invention provides acable-type secondary battery having a horizontal cross section of apredetermined shape and extending longitudinally, comprising: a core forsupplying lithium ions, which comprises an electrolyte; an innerelectrode, comprising an open-structured inner current collectorsurrounding the outer surface of the core for supplying lithium ions, aninner electrode active material layer formed on the surface of the innercurrent collector, and an electrolyte-absorbing layer formed on theouter surface of the inner electrode active material layer; a separationlayer surrounding the outer surface of the inner electrode to prevent ashort circuit between electrodes; and an outer electrode surrounding theouter surface of the separation layer and comprising an outer electrodeactive material layer and an outer current collector.

Also, the present invention provides a cable-type secondary batteryhaving a horizontal cross section of a predetermined shape and extendinglongitudinally, comprising: a core for supplying lithium ions, whichcomprises an electrolyte; an inner electrode, comprising anopen-structured inner current collector surrounding the outer surface ofthe core for supplying lithium ions, an inner electrode active materiallayer formed on the surface of the inner current collector, and anelectrolyte-absorbing layer formed on the outer surface of the innerelectrode active material layer; and an outer electrode surrounding theouter surface of the inner electrode and comprising an outer electrodeactive material layer and an outer current collector.

The open-structured inner current collector is preferably in the form ofa wound wire or a mesh, but is not particularly limited thereto.

In the outer electrode of the cable-type secondary battery having theseparation layer, the outer electrode active material layer may beformed to surround the outer surface of the separation layer, and theouter current collector may be formed to surround the outer surface ofthe outer electrode active material layer; the outer current collectormay be formed to surround the outer surface of the separation layer, andthe outer electrode active material layer may be formed to surround theouter surface of the outer current collector; the outer currentcollector may be formed to surround the outer surface of the separationlayer, and the outer electrode active material layer may be formed tosurround the outer surface of the outer current collector and come intocontact with the separation layer; or the outer electrode activematerial layer may be formed to surround the outer surface of theseparation layer, and the outer current collector may be formed to beincluded inside the outer electrode active material layer by beingcovered therein and to surround the outer surface of the separationlayer with spacing apart therefrom.

Also, in the outer electrode of the cable-type secondary battery havingno separation layer, the outer electrode active material layer may beformed to surround the outer surface of the electrolyte-absorbing layer,and the outer current collector may be formed to surround the outersurface of the outer electrode active material layer; the outer currentcollector may be formed to surround the outer surface of theelectrolyte-absorbing layer, and the outer electrode active materiallayer may be formed to surround the outer surface of the outer currentcollector; the outer current collector may be formed to surround theouter surface of the electrolyte-absorbing layer, and the outerelectrode active material layer may be formed to surround the outersurface of the outer current collector and come into contact with theabsorbing layer; or the outer electrode active material layer may beformed to surround the outer surface of the electrolyte-absorbing layer,and the outer current collector may be formed to be included inside theouter electrode active material layer by being covered therein and tosurround the outer surface of the electrolyte-absorbing layer withspacing apart therefrom.

In the present invention, the outer current collector is notparticularly limited to its forms, but is preferably in the form of apipe, a wound wire, a wound sheet or a mesh.

The inner current collector is not particularly limited to its kinds,but is made of stainless steel, aluminum, nickel, titanium, sinteredcarbon, or copper; stainless steel treated with carbon, nickel, titaniumor silver on the surface thereof; an aluminum-cadmium alloy; anon-conductive polymer treated with a conductive material on the surfacethereof; or a conductive polymer.

Examples of the conductive material which may be used in the presentinvention include polyacetylene, polyaniline, polypyrrole,polythiophene, polysulfurnitride, indium tin oxide (ITO), silver,palladium, nickel, and mixtures thereof.

The outer current collector may be made of stainless steel, aluminum,nickel, titanium, sintered carbon, or copper; stainless steel treatedwith carbon, nickel, titanium or silver on the surface thereof; analuminum-cadmium alloy; a non-conductive polymer treated with aconductive material on the surface thereof; a conductive polymer; ametal paste comprising metal powders of Ni, Al, Au, Ag, Al, Pd/Ag, Cr,Ta, Cu, Ba or ITO; or a carbon paste comprising carbon powders ofgraphite, carbon black or carbon nanotube.

In the present invention, the core for supplying lithium ions comprisesan electrolyte, and examples of the electrolyte may include, but are notparticularly limited to, a non-aqueous electrolyte solution usingethylene carbonate (EC), propylene carbonate (PC), butylene carbonate(BC), vinylene carbonate (VC), diethyl carbonate (DEC), dimethylcarbonate (DMC), ethyl methyl carbonate (EMC), methyl formate (MF),γ-butyrolactone (γ-BL), sulfolane, methyl acetate (MA) or methylpropionate (MP); a gel polymer electrolyte using PEO, PVdF, PVdF-HEP,PMMA, PAN, or PVAc; and a solid electrolyte using PEO, polypropyleneoxide (PPO), polyether imine (PEI), polyethylene sulphide (PES), orpolyvinyl acetate (PVAc). The electrolyte further comprises a lithiumsalt, and the preferred examples of the lithium salt include LiCl, LiBr,LiI, LiClO₄, LiBF₄, LIB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃, LiCF₃CO₂, LiAsF₆,LiSbF₆, LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li, (CF₃SO₂)₂NLi, lithium chloroborate,lower aliphatic lithium carbonate, lithium tetraphenylborate, andmixtures thereof.

The electrolyte-absorbing layer may be made of a polymer selected from agel polymer electrolyte using PEO, PVdF, PVdF-HFP, PMMA, PAN, or PVAc;and a solid electrolyte using PEO, polypropylene oxide (PPO), polyetherimine (PEI), polyethylene sulphide (PES), or polyvinyl acetate (PVAc),but is not particularly limited to thereto, and also, theelectrolyte-absorbing layer may further comprise a lithium salt.

In the present invention, the inner electrode may be an anode and theouter electrode may be a cathode, or the inner electrode may be acathode and the outer electrode may be an anode.

When the inner electrode of the present invention is an anode and theouter electrode is a cathode, the inner electrode active material layermay comprise an active material selected from the group consisting ofnatural graphite, artificial graphite, or carbonaceous material;lithium-titanium complex oxide (LTO), and metals (Me) including Si, Sn,Li, Zn, Mg, Cd, Ce, Ni and Fe; alloys of the metals; oxides (MeOx) ofthe metals; complexes of the metals and carbon; and mixtures thereof,and the outer electrode active material layer may comprise an activematerial selected from the group consisting of LiCoO₂, LiNiO₂, LiMn₂O₄,LiCoPO₄, LiFePO₄, LiNiMnCoO₂, LiNi_(1-x-y-z)Co_(x)M1_(y)M2_(z)O₂(wherein M1 and M2 are each independently selected from the groupconsisting of Al, Ni, Co, Fe, Mn, V, Cr, Ti, W, Ta, Mg and Mo, and x, yand z are each independently an atomic fraction of oxide-formingelements, in which 0≦x<0.5, 0≦y<0.5, 0≦z<0.5, and x+y+z≦1), and mixturesthereof.

Alternatively, when the inner electrode is a cathode and the outerelectrode is an anode, the inner electrode active material layer maycomprise an active material selected from the group consisting ofLiCoO₂, LiNiO₂, LiMn₂O₄, LiCoPO₄, LiFePO₄, LiNiMnCoO₂,LiNi_(1-x-y-z)Co_(x)M1_(y)M2_(z)O₂ (wherein M1 and M2 are eachindependently selected from the group consisting of Al, Ni, Co, Fe, Mn,V, Cr, Ti, W, Ta, Mg and Mo, and x, y and z are each independently anatomic fraction of oxide-forming elements, in which 0≦x<0.5, 0≦y<0.5,0≦z<0.5, and x+y+z≦1), and mixtures thereof, and the outer electrodeactive material layer may comprise an active material selected from thegroup consisting of natural graphite, artificial graphite, orcarbonaceous material; lithium-titanium complex oxide (LTO), and metals(Me) including Si, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe; alloys of themetals; oxides (MeOx) of the metals; complexes of the metals and carbon;and mixtures thereof, but the present invention is not particularlylimited thereto.

In the present invention, the separation layer may be an electrolytelayer or a separator.

The electrolyte layer is not particularly limited to its kinds, butpreferably is made of an electrolyte selected from a gel polymerelectrolyte using PEO, PVdF, PVdF-HFP, PMMA, PAN, or PVAc; and a solidelectrolyte of PEO, polypropylene oxide (PPO), polyether imine (PEI),polyethylene sulphide (PES), or polyvinyl acetate (PVAc). Also, theelectrolyte layer may further comprise a lithium salt, and non-limitingexamples of the lithium salt include LiCl, LiBr, LiI, LiClO₄, LiBF₄,LiB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃, LiCF₃CO₂, LiAsF₆, LiSbF₆, LiAlCl₄, CH₃SO₃Li,CF₃SO₃Li, (CF₃SO₂)₂NLi, lithium chloroborate, lower aliphatic lithiumcarbonate, lithium tetraphenylborate, and mixtures thereof.

When the separation layer is a separator, the cable-type secondarybattery of the present invention needs an electrolyte solution, andexamples of the separator may include, but is not limited to, a poroussubstrate made of a polyolefin-based polymer selected from the groupconsisting of ethylene homopolymers, propylene homopolymers,ethylene-butene copolymers, ethylene-hexene copolymers, andethylene-methacrylate copolymers; a porous substrate made of a polymerselected from the group consisting of polyesters, polyacetals,polyamides, polycarbonates, polyimides, polyether ether ketones,polyether sulfones, polyphenylene oxides, polyphenylene sulfides andpolyethylene naphthalenes; or a porous substrate made of a mixture ofinorganic particles and a binder polymer.

Further, the present invention provides a cable-type secondary batteryhaving multiple inner electrodes, and also a cable-type secondarybattery having multiple inner electrodes with a separation layer.

Advantageous Effects

In accordance with the present invention, a core for supplying lithiumions, which comprises an electrolyte, is disposed in the inner electrodehaving an open structure, from which the electrolyte of the core forsupplying lithium ions can be easily penetrated into an electrode activematerial, thereby facilitating the supply and exchange of lithium ions.Also, the inner electrode of the present invention has anelectrolyte-absorbing layer on the outer surface thereof, from which theelectrolyte of the core for supplying lithium ions can be contained inthe inner electrode, thereby assisting the supply and exchange oflithium ions. Accordingly, the cable-type secondary battery of thepresent invention has such a core for supplying lithium ions to exhibitsuperior capacity and cycle characteristics. Also, the cable-typesecondary battery of the present invention has an inner electrode havingan open structure to exhibit good flexibility.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate preferred embodiments of thepresent invention and, together with the foregoing disclosure, serve toprovide further understanding of the technical spirit of the presentinvention. However, the present invention is not to be construed asbeing limited to the drawings.

FIG. 1 is a perspective view showing a cable-type secondary batteryhaving one inner electrode in the form of a mesh and a separation layerin accordance with one embodiment of the present invention.

FIG. 2 is a perspective view showing a cable-type secondary batteryhaving one inner electrode in the form of a mesh in accordance with oneembodiment of the present invention.

FIG. 3 is a perspective view showing a cable-type secondary batteryhaving one inner electrode in the form of a wound wire and a separationlayer in accordance with one embodiment of the present invention.

FIG. 4 is a perspective view showing a cable-type secondary batteryhaving one inner electrode in the form of a wound wire in accordancewith one embodiment of the present invention.

FIG. 5 is a perspective view showing a cable-type secondary batteryhaving multiple inner electrodes and a separation layer in accordancewith one embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a cable-type secondary batteryhaving multiple inner electrodes in accordance with one embodiment ofthe present invention.

BEST MODE

Hereinafter, the present invention will be described in detail withreference to the accompanying drawings. Prior to the description, itshould be understood that the terms used in the specification and theappended claims should not be construed as limited to general anddictionary meanings, but interpreted based on the meanings and conceptscorresponding to technical aspects of the present invention on the basisof the principle that the inventor is allowed to define termsappropriately for the best explanation. FIG. 1 schematically shows acable-type secondary battery having one inner electrode in the form of amesh and a separation layer in accordance with one embodiment of thepresent invention. However, the configurations illustrated in thedrawings and the embodiments are just preferable examples for thepurpose of illustrations only, not intended to limit the scope of thedisclosure, so it should be understood that other equivalents andmodifications could be made thereto without departing from the spiritand scope of the disclosure.

Referring to FIG. 1, a cable-type secondary battery 100 has a horizontalcross section of a predetermined shape and extending longitudinally, andcomprises a core 110 for supplying lithium ions, which comprises anelectrolyte; an inner electrode 120, comprising an open-structured innercurrent collector surrounding the outer surface of the core forsupplying lithium ions, an inner electrode active material layer formedon the surface of the inner current collector, and anelectrolyte-absorbing layer formed on the outer surface of the innerelectrode active material layer; a separation layer 130 surrounding theouter surface of the inner electrode to prevent a short circuit betweenelectrodes; and an outer electrode surrounding the outer surface of theseparation layer and comprising an outer electrode active material layerand an outer current collector.

In the present invention, the outer electrode may be formed in variousembodiments depending on the disposition of the outer electrode activematerial layer and the outer current collector, which come into contactwith the separation layer.

In FIG. 1, the outer electrode comprises an outer electrode activematerial layer 140 surrounding the outer surface of the separation layer130 and an outer current collector 150 surrounding the outer surface ofthe outer electrode active material layer.

Also, the outer electrode of the cable-type secondary battery accordingto one embodiment of the present invention may be formed in a structurehaving the outer current collector formed to surround the outer surfaceof the separation layer, and the outer electrode active material layerformed to surround the outer surface of the outer current collector; astructure having the outer current collector formed to surround theouter surface of the separation layer, and the outer electrode activematerial layer formed to surround the outer surface of the outer currentcollector and to come into contact with the separation layer; or astructure having the outer electrode active material layer formed tosurround the outer surface of the separation layer, and the outercurrent collector formed to be included inside the outer electrodeactive material layer by being covered therein and to surround the outersurface of the separation layer with spacing apart therefrom.

The term ‘a predetermined shape’ used herein refers to not beingparticularly limited to any shape, and means that any shape that doesnot damage the nature of the present invention is possible. Thecable-type secondary battery of the present invention has a horizontalcross section of a predetermined shape, a linear structure, whichextends in the longitudinal direction, and flexibility, so it can freelychange in shape. Also, the term ‘open-structured’ used herein means thata structure has an open boundary surface through which a substance maybe transferred freely from the inside of the structure to the outsidethereof.

The conventional cable-type secondary batteries have an electrolytelayer which is interposed between an inner electrode and an outerelectrode. In order for the electrolyte layer to isolate the innerelectrode from the outer electrode and prevent a short circuit, theelectrolyte layer is required to be made of gel-type polymerelectrolytes or solid polymer electrolytes having a certain degree ofmechanical properties. However, such gel-type polymer electrolytes orsolid polymer electrolytes fail to provide superior performances as asource for lithium ions, so an electrolyte layer made of such shouldhave an increased thickness so as to sufficiently provide lithium ions.Such a thickness increase in the electrolyte layer widens an intervalbetween the electrodes to cause resistance increase, therebydeteriorating battery performances. In contrast, as the cable-typesecondary battery 100 of the present invention has the core 110 forsupplying lithium ions, which comprises an electrolyte, and the innerelectrode 120 of the present invention has the open-structured innercurrent collector, the electrolyte of the core 110 for supplying lithiumions can pass through the inner current collector of the inner electrode120 to reach the inner electrode active material layer and the outerelectrode active material layer 140. Accordingly, it is not necessary toexcessively increase the thickness of an electrolyte layer. Also, anelectrolyte layer may not be adopted as an essential component, andtherefore, only a separator may be optionally used. Thus, the cable-typesecondary battery of the present invention has the core 110 forsupplying lithium ions, which comprises an electrolyte, to facilitatethe penetration of an electrolyte into an electrode active material, andeventually facilitate the supply and exchange of lithium ions inelectrodes, thereby exhibiting superior capacity and cyclecharacteristics.

The inner electrode 120 of the present invention maintains its openstructure by forming the inner electrode active material layer by way ofcoating on the surface of the open-structured inner current collector,in which the electrolyte-absorbing layer is also formed on the surfaceof the inner electrode active material layer. The electrolyte-absorbinglayer may contain the electrolyte of the core 110 for supplying lithiumions, and also comprise a lithium salt, to facilitate the supply andexchange of lithium ions in electrodes, thereby providing superiorcapacity and cycle characteristics to the battery. This inner electrode120 has the open-structured inner current collector, which allows thepenetration of the electrolyte comprised in the core 110 for supplyinglithium ions, and the open structure form may be any form if itfacilitates the penetration of the electrolyte. Referring to FIGS. 1 and3, as a non-limiting example of the open-structured inner currentcollector, an inner electrode 320 applying a wound wire-type innercurrent collector, and an inner electrode 120 applying a mesh-form innercurrent collector are illustrated.

The core 110 for supplying lithium ions comprises an electrolyte, andexamples of the electrolyte may include, but are not particularlylimited to, a non-aqueous electrolyte solution using ethylene carbonate(EC), propylene carbonate (PC), butylene carbonate (BC), vinylenecarbonate (VC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), methyl formate (MF), γ-butyrolactone (γ-BL),sulfolane, methyl acetate (MA) or methyl propionate (MP); a gel polymerelectrolyte using PEO, PVdF, PVdF-HEP, PMMA, PAN, or PVAc; and a solidelectrolyte using PEO, polypropylene oxide (PPO), polyether imine (PEI),polyethylene sulphide (PES), or polyvinyl acetate (PVAc). Theelectrolyte further comprises a lithium salt, and the preferred examplesof the lithium salt include LiCl, LiBr, LiI, LiClO₄, LiBF₄, LiB₁₀Cl₁₀,LiPF₆, LiCF₃SO₃, LiCF₃CO₂, LiASF₆, LiSbF₆, LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li,(CF₃SO₂)₂NLi, lithium chloroborate, lower aliphatic lithium carbonate,lithium tetraphenylborate, and the like. Also, the core 110 forsupplying lithium ions may consist of only an electrolyte, and in thecase of a liquid electrolyte, a porous carrier may be used together.

The inner current collector is preferably made of stainless steel,aluminum, nickel, titanium, sintered carbon, or copper; stainless steeltreated with carbon, nickel, titanium or silver on the surface thereof;an aluminum-cadmium alloy; a non-conductive polymer treated with aconductive material on the surface thereof; or a conductive polymer.

The current collector serves to collect electrons generated byelectrochemical reaction of the active material or to supply electronsrequired for the electrochemical reaction. In general, the currentcollector is made of a metal such as copper or aluminum. Especially,when the current collector is made of a non-conductive polymer treatedwith a conductive material on the surface thereof or a conductivepolymer, the current collector has a relatively higher flexibility thanthe current collector made of a metal such as copper or aluminum. Also,a polymer current collector may be used instead of the metal currentcollector to reduce the weight of the battery.

The conductive material may include polyacetylene, polyaniline,polypyrrole, polythiophene, polysulfurnitride, indium tin oxide (ITO),copper, silver, palladium, nickel, etc. The conductive polymer mayinclude polyacetylene, polyaniline, polypyrrole, polythiophene,polysulfurnitride, etc. However, the non-conductive polymer used for thecurrent collector is not particularly limited to its kinds.

In the present invention, the inner electrode active material layer isformed on the surface of the inner current collector which preferablymaintains an open structure form. On the surface of the inner electrodeactive material layer, the electrolyte-absorbing layer is formed. Theelectrolyte-absorbing layer may comprise a polymer selected from a gelpolymer electrolyte using PEO, PVdF, PVdF-HFP, PMMA, PAN, or PVAc; and asolid electrolyte using PEO, polypropylene oxide (PPO), polyether imine(PEI), polyethylene sulphide (PES), or polyvinyl acetate (PVAc), but isnot particularly limited thereto. Also, the electrolyte-absorbing layermay further comprise a lithium salt, and the preferred examples of thelithium salt include LiCl, LiBr, LiI, LiClO₄, LiBF₄, LiB₁₀Cl₁₀, LiPF₆,LiCF₃SO₃, LiCF₃CO₂, LiAsF₆, LiSbF₆, LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li,(CF₃SO₂)₂NLi, lithium chloroborate, lower aliphatic lithium carbonate,lithium tetraphenylborate, and the like.

In the present invention, the outer current collector is notparticularly limited to its forms, but is preferably in the form of apipe, a wound wire, a wound sheet or a mesh. The outer current collectormay be made of stainless steel, aluminum, nickel, titanium, sinteredcarbon, or copper; stainless steel treated with carbon, nickel, titaniumor silver on the surface thereof; an aluminum-cadmium alloy; anon-conductive polymer treated with a conductive material on the surfacethereof; a conductive polymer; a metal paste comprising metal powders ofNi, Al, Au, Ag, Al, Pd/Ag, Cr, Ta, Cu, Ba or ITO; or a carbon pastecomprising carbon powders of graphite, carbon black or carbon nanotube.

The inner electrode may be an anode and the outer electrode may be acathode. Alternatively, the inner electrode may be a cathode and theouter electrode may be an anode.

In the present invention, the electrode active material layer allowsions to move through the current collector, and the movement of ions iscaused by the interaction of ions such as intercalation/deintercalationof ions into and from the electrolyte layer. Such an electrode activematerial layer may be divided into an anode active material layer and acathode active material layer.

Specifically, when the inner electrode is an anode and the outerelectrode is a cathode, the inner electrode active material layerbecomes an anode active material layer and may be made of an activematerial selected from the group consisting of natural graphite,artificial graphite, or carbonaceous material; lithium-titanium complexoxide (LTO), and metals (Me) including Si, Sn, Li, Zn, Mg, Cd, Ce, Niand Fe; alloys of the metals; oxides (MeOx) of the metals; complexes ofthe metals and carbon; and mixtures thereof, and the outer electrodeactive material layer becomes a cathode active material layer and may bemade of an active material selected from the group consisting of LiCoO₂,LiNiO₂, LiMn₂O₄, LiCoPO₄, LiFePO₄, LiNiMnCoO₂,LiNi_(1-x-y-z)Co_(x)M1_(y)M2_(z)O₂ (wherein M1 and M2 are eachindependently selected from the group consisting of Al, Ni, Co, Fe, Mn,V, Cr, Ti, W, Ta, Mg and Mo, and x, y and z are each independently anatomic fraction of oxide-forming elements, in which 0≦x<0.5, 0≦y<0.5,0≦z<0.5, and x+y+z≦1), and mixtures thereof.

Alternatively, when the inner electrode is a cathode and the outerelectrode is an anode, the inner electrode active material layer becomesa cathode active material layer and the outer electrode active materiallayer becomes an anode active material layer.

As mentioned above, referring to FIG. 1, the outer electrode comprisesan outer electrode active material layer 140 surrounding the outersurface of the separation layer 130 and an outer current collector 150surrounding the outer surface of the outer electrode active materiallayer 140.

Also, the outer electrode may have the outer current collector formed tosurround the outer surface of the separation layer, and the outerelectrode active material layer formed to surround the outer surface ofthe outer current collector; may have the outer current collector formedto surround the outer surface of the separation layer, and the outerelectrode active material layer formed to surround the outer surface ofthe outer current collector and to come into contact with the separationlayer; or may have the outer electrode active material layer formed tosurround the outer surface of the separation layer, and the outercurrent collector formed to be included inside the outer electrodeactive material layer by being covered therein and to surround the outersurface of the separation layer with spacing apart therefrom.

Specifically, if the outer current collector is wound on the outersurface of the separation layer, a contact area of the separation layerand the active material layer sufficiently increases to ensure a certaindegree of battery performances. Particularly, since the outer electrodeactive material layer of the present invention is formed by coating anactive material in the form of a slurry on the outer surface of theouter current collector, the outer electrode active material layer comesinto contact with the separation layer. Also, the outer currentcollector is included inside the outer electrode active material layerby being covered therein, while surrounding the outer surface of theseparation layer with spacing apart therefrom by the outer electrodeactive material layer. As a result, an electric contact between theouter current collector and the outer electrode active material layer isimproved, thereby contributing to the enhancement of batterycharacteristics.

For example, when the outer current collector is in the form of a woundwire having flexibility, the wound wire-form outer current collector haselasticity due to its form to enhance the overall flexibility of thecable-type secondary battery. Also, when excessive external force isapplied to the cable-type secondary battery of the present invention,the wire-form outer current collector of the present invention undergoesvery little excessive deformation such as crumpling or bending, so ashort circuit due to a contact with an inner current collector may beavoided.

The electrode active material layer comprises an electrode activematerial, a binder and a conductive material, and is combined with acurrent collector to configure an electrode. If the electrode isdeformed by bending or severely folding due to external force, theelectrode active material may be released. The release of the electrodeactive material deteriorates the performance and capacity of batteries.However, in accordance with the present invention, the wound wire-formouter current collector having elasticity functions to disperse theapplied force when such a deformation occurs by the external force, fromwhich the active material layer is less deformed, thereby preventing therelease of the active material. The separation layer of the presentinvention may be an electrolyte layer or a separator.

The electrolyte layer serving as an ion channel may be made of agel-type polymer electrolyte using PEO, PVdF, PVdF-HFP, PMMA, PAN orPVAC, or a solid electrolyte using PEO, polypropylene oxide (PPO),polyethylene imine (PEI), polyethylene sulfide (PES) or polyvinylacetate (PVAc). The matrix of the solid electrolyte is preferably formedusing a polymer or a ceramic glass as the backbone. In the case of thetypical polymer electrolytes, the ions move very slowly in terms ofreaction rate, even when the ionic conductivity is satisfied. Thus, thegel-type polymer electrolyte which facilitates the movement of ions ispreferably used compared to the solid electrolyte. The gel-type polymerelectrolyte has poor mechanical properties and thus may comprise aporous support or a cross-linked polymer to improve the poor mechanicalproperties. The electrolyte layer of the present invention can serve asa separator, and thus an additional separator may be omitted.

The electrolyte layer of the present invention may further comprise alithium salt. The lithium salt can improve an ionic conductivity andresponse time. Non-limiting examples of the lithium salt may includeLiCl, LiBr, LiI, LiClO₄, LiBF₄, LiB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃, LiCF₃CO₂,LiAsF₆, LiSbF₆, LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li, (CF₃SO₂)₂NLi, lithiumchloroborate, lower aliphatic lithium carbonate, and lithiumtetraphenylborate.

Examples of the separator may include, but is not limited to, a poroussubstrate made of a polyolefin-based polymer selected from the groupconsisting of ethylene homopolymers, propylene homopolymers,ethylene-butene copolymers, ethylene-hexene copolymers, andethylene-methacrylate copolymers; a porous substrate made of a polymerselected from the group consisting of polyesters, polyacetals,polyamides, polycarbonates, polyimides, polyether ether ketones,polyether sulfones, polyphenylene oxides, polyphenylene sulfides andpolyethylene naphthalenes; or a porous substrate made of a mixture ofinorganic particles and a binder polymer. Among these, in order for thelithium ions of the core for supplying lithium ions to be transferred tothe outer electrode, it is preferred to use a non-woven fabric separatorcorresponding to the porous substrate made of a polymer selected fromthe group consisting of polyesters, polyacetals, polyamides,polycarbonates, polyimides, polyether ether ketones, polyether sulfones,polyphenylene oxides, polyphenylene sulfides and polyethylenenaphthalenes.

Also, the cable-type secondary battery of the present invention has aprotection coating. The protection coating is an insulator and is formedto surround the outer current collector, thereby protecting theelectrodes against moisture in the air and external impacts. Theprotection coating may be made of conventional polymer resins, forexample, PVC, HDPE or epoxy resins.

Also, the cable-type secondary battery of the present invention may nothave the separation layer.

Referring to FIG. 2, a cable-type secondary battery 200 according to oneembodiment of the present invention comprises a core 210 for supplyinglithium ions, which comprises an electrolyte; an inner electrode 220,comprising an open-structured inner current collector surrounding theouter surface of the core for supplying lithium ions, an inner electrodeactive material layer formed on the surface of the inner currentcollector, and an electrolyte-absorbing layer formed on the outersurface of the inner electrode active material layer; and an outerelectrode comprising an outer electrode active material layer 240surrounding the outer surface of the inner electrode and an outercurrent collector 250 surrounding the outer surface of the outerelectrode active material layer 240. The inner electrode 220 of thepresent invention has the electrolyte-absorbing layer on the outermostsurface thereof, thereby preventing a short circuit between the innerelectrode and the outer electrode. Accordingly, the separation layer maynot be essential.

Also, the outer electrode may have the outer current collector formed tosurround the outer surface of the electrolyte-absorbing layer, and theouter electrode active material layer formed to surround the outersurface of the outer current collector; may have the outer currentcollector formed to surround the outer surface of theelectrolyte-absorbing layer, and the outer electrode active materiallayer formed to surround the outer surface of the outer currentcollector and to come into contact with the electrolyte-absorbing layer;or may have the outer electrode active material layer formed to surroundthe outer surface of the electrolyte-absorbing layer, and the outercurrent collector formed to be included inside the outer electrodeactive material layer by being covered therein and to surround the outersurface of the electrolyte-absorbing layer with spacing apart therefrom.

Specifically, if the outer current collector is wound on the outersurface of the electrolyte-absorbing layer, similar to the case that theouter current collector is wound on the outer surface of the separationlayer, a contact area of the electrolyte-absorbing layer and the activematerial layer sufficiently increases to ensure a certain degree ofbattery performances. Particularly, since the outer electrode activematerial layer of the present invention is formed by coating an activematerial in the form of a slurry on the outer surface of the outercurrent collector, the outer electrode active material layer comes intocontact with the electrolyte-absorbing layer. Also, the outer currentcollector is included inside the outer electrode active material layerby being covered therein, while surrounding the outer surface of theelectrolyte-absorbing layer with spacing apart therefrom by the outerelectrode active material layer. As a result, an electric contactbetween the outer current collector and the outer electrode activematerial layer is improved, thereby contributing to the enhancement ofbattery characteristics.

Hereinafter, a cable-type secondary battery according to one embodimentof the present invention and the manufacture thereof will be brieflyexplained with reference to FIG. 1.

A cable-type secondary battery 100 according to one embodiment of thepresent invention comprises a core 110 for supplying lithium ions, whichcomprises an electrolyte; an inner electrode 120, comprising a mesh-forminner current collector surrounding the outer surface of the core forsupplying lithium ions, an inner electrode active material layer formedon the surface of the inner current collector, and anelectrolyte-absorbing layer formed on the outer surface of the innerelectrode active material layer; a separation layer 130 surrounding theouter surface of the inner electrode to prevent a short circuit betweenelectrodes; and an outer electrode comprising an outer electrode activematerial layer 140 surrounding the outer surface of the separation layerand an outer current collector 150 surrounding the outer surface of theouter electrode active material layer.

First, a polymer electrolyte is provided in the form of a wire using anextruder to prepare the core 110 for supplying lithium ions. Also, thecore 110 for supplying lithium ions may be formed by providing a hollowinner electrode and introducing a non-aqueous electrolyte solution inthe center of the inner electrode, or may be formed by providing abattery assembly comprising a protection coating as well as the othersand introducing a non-aqueous electrolyte solution in the center of theinner electrode support comprised in the battery assembly.Alternatively, the core 110 for supplying lithium ions may be preparedby providing a wire-form carrier made of a sponge material andintroducing a non-aqueous electrolyte solution thereto.

Then, a mesh-form inner current collector is provided, and an innerelectrode active material layer is formed by way of coating on thesurface of the mesh-form inner current collector. The coating may becarried out by various conventional methods, for example, by anelectroplating process or an anodic oxidation process. Also, in order tomaintain constant intervals, an electrode slurry containing an activematerial may be discontinuously applied by way of an extrusion-coatingusing an extruder. In addition, the electrode slurry containing anactive material may be applied by way of dip coating orextrusion-coating using an extruder.

On the surface of the inner electrode active material layer formed byway of coating, an electrolyte-absorbing layer is formed by way of dipcoating or extrusion-coating using an extruder, to prepare the innerelectrode 120. The inner electrode 120 thus prepared is applied on theouter surface of the core 110 for supplying lithium ions.

Subsequently, the separation layer 130 made of a non-woven fabric isformed to surround the inner electrode 120.

On the outer surface of the separation layer 130 formed by the coatingof an electrolyte, the outer electrode active material layer 140 isformed by way of coating. The coating method of the inner electrodeactive material layer may be identically applied to the outer electrodeactive material layer 140.

Then, an outer current collector in the form of a wire is provided andwound on the outer surface of the outer electrode active material layer140 to form the wound wire-form outer current collector. As the outercurrent collector, a wound sheet-, pipe- or mesh-form current collectormay be used. At this time, the outer electrode active material layer maybe first formed on the outer current collector and then the separationlayer is applied thereon, to form the outer electrode. For example, inthe case of the wound sheet-form current collector, the outer electrodeactive material layer may be first formed on the wound sheet-formcurrent collector, followed by cutting into a piece having apredetermined size, to prepare a sheet-form outer electrode. Then, theprepared sheet-form outer electrode may be wound on the outer surface ofthe separation layer so that the outer electrode active material layercomes into contact with the separation layer, to form the outerelectrode on the separation layer.

As another method, in the formation of the outer electrode, the outercurrent collector may be first formed to surround the outer surface ofthe separation layer, and then followed by forming the outer electrodeactive material layer to surround the outer surface of the outer currentcollector.

Meanwhile, in the case of a structure having the outer current collectorformed to surround the outer surface of the separation layer, and theouter electrode active material layer formed to surround the outersurface of the outer current collector and to come into contact with theseparation layer, first, an outer current collector, for example, in theform of a wire or sheet, is wound on the outer surface of the separationlayer. The winding method is not particularly limited. For example, inthe case of the wire-form current collector, the winding may be carriedout by using a winding machine on the outer surface of the separationlayer. Then, the outer electrode active material layer is formed by wayof coating on the outer surface of the wound wire- or sheet-form outercurrent collector so that the outer electrode active material layersurrounds the outer current collector and comes into contact with theseparation layer.

Also, in the case of a structure having the outer electrode activematerial layer formed to surround the outer surface of the separationlayer, and the outer current collector formed to be included inside theouter electrode active material layer by being covered therein and tosurround the outer surface of the separation layer with spacing aparttherefrom, first, on the outer surface of the separation layer, a partof the outer electrode active material layer to be finally obtained isformed, on which the outer current collector is formed to surround thepart of the outer electrode active material layer, and then the outerelectrode active material layer is further formed on the outer currentcollector to completely cover the outer current collector. Thereby, theouter current collector is disposed inside the outer electrode activematerial layer to improve an electric contact between the currentcollector and the active material, thereby enhancing batterycharacteristics.

Finally, the protection coating 160 is formed to surround the outersurface of the electrode assembly. The protection coating 160 is aninsulator and is formed on the outermost surface for the purpose ofprotecting the electrodes against moisture in the air and externalimpacts. As the protection coating 160, conventional polymer resins, forexample, PVC, HDPE and epoxy resins may be used.

Hereinafter, other embodiments of the present invention will be brieflyexplained with reference to FIGS. 2, 3 and 4.

Referring to FIG. 2, a cable-type secondary battery 200 according to oneembodiment of the present invention comprises a core 210 for supplyinglithium ions, which comprises an electrolyte; an inner electrode 220,comprising a mesh-form inner current collector surrounding the outersurface of the core for supplying lithium ions, an inner electrodeactive material layer formed on the surface of the inner currentcollector, and an electrolyte-absorbing layer formed on the outersurface of the inner electrode active material layer; and an outerelectrode comprising an outer electrode active material layer 240surrounding the outer surface of the inner electrode and an outercurrent collector 250 surrounding the outer surface of the outerelectrode active material layer. Such a cable-type secondary battery 200does not comprise the separation layer 130, unlike the cable-typesecondary battery 100 of FIG. 1.

Referring to FIG. 3, a cable-type secondary battery 300 according to oneembodiment of the present invention comprises a core 310 for supplyinglithium ions, which comprises an electrolyte; an inner electrode 320,comprising a wound wire-form inner current collector surrounding theouter surface of the core for supplying lithium ions, an inner electrodeactive material layer formed on the surface of the inner currentcollector, and an electrolyte-absorbing layer formed on the outersurface of the inner electrode active material layer; a separation layer330 surrounding the outer surface of the inner electrode to prevent ashort circuit between electrodes; and an outer electrode comprising anouter electrode active material layer 340 surrounding the outer surfaceof the separation layer and an outer current collector 350 surroundingthe outer surface of the outer electrode active material layer.

Referring to FIG. 4, a cable-type secondary battery 400 according to oneembodiment of the present invention comprises a core 410 for supplyinglithium ions, which comprises an electrolyte; an inner electrode 420,comprising a wound wire-form inner current collector surrounding theouter surface of the core for supplying lithium ions, an inner electrodeactive material layer formed on the surface of the inner currentcollector, and an electrolyte-absorbing layer formed on the outersurface of the inner electrode active material layer; and an outerelectrode comprising an outer electrode active material layer 440surrounding the outer surface of the inner electrode and an outercurrent collector 450 surrounding the outer surface of the outerelectrode active material layer. Such a cable-type secondary battery 400does not comprise the separation layer 330, unlike the cable-typesecondary battery 300 of FIG. 3.

Hereinafter, still other embodiments of the present invention will bebriefly explained with reference to FIGS. 5 and 6.

Referring to FIG. 5, a cable-type secondary battery 500 according to oneembodiment of the present invention comprises two or more cores 510 forsupplying lithium ions, which comprise an electrolyte; two or more innerelectrodes 520 arranged parallel to each other, each inner electrodecomprising an open-structured inner current collector surrounding theouter surface of each core for supplying lithium ions, an innerelectrode active material layer formed on the surface of the innercurrent collector, and an electrolyte-absorbing layer formed on theouter surface of the inner electrode active material layer; a separationlayer 530 surrounding the outer surface of the inner electrodes 520 toprevent a short circuit between electrodes; and an outer electrodecomprising an outer electrode active material layer 540 surrounding theouter surface of the separation layer 530 and an outer current collector550 surrounding the outer surface of the outer electrode active materiallayer 540. Such a cable-type secondary battery 500 has the innerelectrode consisting of multiple electrodes, thereby allowing to controlthe balance between a cathode and anode and prevent a short circuit.

Referring to FIG. 6, a cable-type secondary battery 600 according to oneembodiment of the present invention comprises two or more cores 610 forsupplying lithium ions, which comprise an electrolyte; two or more innerelectrodes 620 arranged parallel to each other, each inner electrodecomprising an open-structured inner current collector surrounding theouter surface of each core for supplying lithium ions, an innerelectrode active material layer formed on the surface of the innercurrent collector, and an electrolyte-absorbing layer formed on theouter surface of the inner electrode active material layer; and an outerelectrode comprising an outer electrode active material layer 640surrounding the outer surface of the inner electrode and an outercurrent collector 650 surrounding the outer surface of the outerelectrode active material layer 640. Such a cable-type secondary battery600 does not comprise the separation layer 530, unlike the cable-typesecondary battery 500 of FIG. 5.

Also, in the cable-type secondary battery of FIG. 3 and the cable-typesecondary battery having the inner electrode consisting of multipleelectrodes of FIG. 5, besides the structure of the outer electrodehaving the outer electrode active material layer formed to surround theouter surface of the separation layer, and the outer current collectorformed to surround the outer surface of the outer electrode activematerial layer, as mentioned above, the outer electrode may be formed ina structure having the outer current collector formed to surround theouter surface of the separation layer, and the outer electrode activematerial layer formed to surround the outer surface of the outer currentcollector; a structure having the outer current collector formed tosurround the outer surface of the separation layer, and the outerelectrode active material layer formed to surround the outer surface ofthe outer current collector and to come into contact with the separationlayer; or a structure having the outer electrode active material layerformed to surround the outer surface of the separation layer, and theouter current collector formed to be included inside the outer electrodeactive material layer by being covered therein and to surround the outersurface of the separation layer with spacing apart therefrom.

Meanwhile, in the cable-type secondary battery of FIG. 4 and thecable-type secondary battery having the inner electrode consisting ofmultiple electrodes of FIG. 6, since the separation layer is not used,the outer electrode is formed on the outer surface of theelectrolyte-absorbing layer.

In this case, besides the structure having the outer electrode activematerial layer formed to surround the outer surface of theelectrolyte-absorbing layer, and the outer current collector formed tosurround the outer surface of the outer electrode active material layer,as mentioned above, the outer electrode may be formed in a structurehaving the outer current collector formed to surround the outer surfaceof the electrolyte-absorbing layer, and the outer electrode activematerial layer formed to surround the outer surface of the outer currentcollector; a structure having the outer current collector formed tosurround the outer surface of the electrolyte-absorbing layer, and theouter electrode active material layer formed to surround the outersurface of the outer current collector and come into contact with theabsorbing layer; or a structure having the outer electrode activematerial layer formed to surround the outer surface of theelectrolyte-absorbing layer, and the outer current collector formed tobe included inside the outer electrode active material layer by beingcovered therein and to surround the outer surface of theelectrolyte-absorbing layer with spacing apart therefrom.

EXPLANATION OF REFERENCE NUMERALS

-   100, 200, 300, 400, 500, 600: Cable-type Secondary Battery-   110, 210, 310, 410, 510, 610: Core for Supplying Lithium Ions-   120, 220, 320, 420, 520, 620: Inner Electrode-   130, 330, 530: Separation Layer-   140, 240, 340, 440, 540, 640: Outer Electrode Active Material Layer-   150, 250, 350, 450, 550, 650: Outer Current Collector-   160, 260, 360, 460, 560, 660: Protection Coating

What is claimed is:
 1. A cable-type secondary battery having ahorizontal cross section of a predetermined shape and extendinglongitudinally, comprising: a core for supplying lithium ions, whichcomprises an electrolyte; an inner electrode, comprising anopen-structured inner current collector surrounding the outer surface ofthe core for supplying lithium ions, an inner electrode active materiallayer formed on the surface of the inner current collector, and anelectrolyte-absorbing layer formed on the outer surface of the innerelectrode active material layer; a separation layer surrounding theouter surface of the inner electrode to prevent a short circuit betweenelectrodes; and an outer electrode surrounding the outer surface of theseparation layer and comprising an outer electrode active material layerand an outer current collector.
 2. A cable-type secondary battery havinga horizontal cross section of a predetermined shape and extendinglongitudinally, comprising: a core for supplying lithium ions, whichcomprises an electrolyte; an inner electrode, comprising anopen-structured inner current collector surrounding the outer surface ofthe core for supplying lithium ions, an inner electrode active materiallayer formed on the surface of the inner current collector, and anelectrolyte-absorbing layer formed on the outer surface of the innerelectrode active material layer; and an outer electrode surrounding theouter surface of the inner electrode and comprising an outer electrodeactive material layer and an outer current collector.
 3. The cable-typesecondary battery according to claim 1, wherein the open-structuredinner current collector is in the form of a wound wire or a mesh.
 4. Thecable-type secondary battery according to claim 1, wherein in the outerelectrode, the outer electrode active material layer is formed tosurround the outer surface of the separation layer, and the outercurrent collector is formed to surround the outer surface of the outerelectrode active material layer; the outer current collector is formedto surround the outer surface of the separation layer, and the outerelectrode active material layer is formed to surround the outer surfaceof the outer current collector; the outer current collector is formed tosurround the outer surface of the separation layer, and the outerelectrode active material layer is formed to surround the outer surfaceof the outer current collector and come into contact with the separationlayer; or the outer electrode active material layer is formed tosurround the outer surface of the separation layer, and the outercurrent collector is formed to be included inside the outer electrodeactive material layer by being covered therein and to surround the outersurface of the separation layer with spacing apart therefrom.
 5. Thecable-type secondary battery according to claim 2, wherein in the outerelectrode, the outer electrode active material layer is formed tosurround the outer surface of the electrolyte-absorbing layer, and theouter current collector is formed to surround the outer surface of theouter electrode active material layer; the outer current collector isformed to surround the outer surface of the electrolyte-absorbing layer,and the outer electrode active material layer is formed to surround theouter surface of the outer current collector; the outer currentcollector is formed to surround the outer surface of theelectrolyte-absorbing layer, and the outer electrode active materiallayer is formed to surround the outer surface of the outer currentcollector and come into contact with the absorbing layer; or the outerelectrode active material layer is formed to surround the outer surfaceof the electrolyte-absorbing layer, and the outer current collector isformed to be included inside the outer electrode active material layerby being covered therein and to surround the outer surface of theelectrolyte-absorbing layer with spacing apart therefrom.
 6. Thecable-type secondary battery according to claim 1, wherein the outercurrent collector is in the form of a pipe, a wound wire, a wound sheetor a mesh.
 7. The cable-type secondary battery according to claim 1,wherein the inner current collector is made of stainless steel,aluminum, nickel, titanium, sintered carbon, or copper; stainless steeltreated with carbon, nickel, titanium or silver on the surface thereof;an aluminum-cadmium alloy; a non-conductive polymer treated with aconductive material on the surface thereof; or a conductive polymer. 8.The cable-type secondary battery according to claim 7, wherein theconductive material is selected from the group consisting ofpolyacetylene, polyaniline, polypyrrole, polythiophene,polysulfurnitride, indium tin oxide (ITO), silver, palladium, nickel,and mixtures thereof.
 9. The cable-type secondary battery according toclaim 7, wherein the conductive polymer is selected from the groupconsisting of polyacetylene, polyaniline, polypyrrole, polythiophene,polysulfurnitride, and mixtures thereof.
 10. The cable-type secondarybattery according to claim 1, wherein the outer current collector ismade of stainless steel, aluminum, nickel, titanium, sintered carbon, orcopper; stainless steel treated with carbon, nickel, titanium or silveron the surface thereof; an aluminum-cadmium alloy; a non-conductivepolymer treated with a conductive material on the surface thereof; aconductive polymer; a metal paste comprising metal powders of Ni, Al,Au, Ag, Al, Pd/Ag, Cr, Ta, Cu, Ba or ITO; or a carbon paste comprisingcarbon powders of graphite, carbon black or carbon nanotube.
 11. Thecable-type secondary battery according to claim 1, wherein theelectrolyte comprises an electrolyte selected from a non-aqueouselectrolyte solution using ethylene carbonate (EC), propylene carbonate(PC), butylene carbonate (BC), vinylene carbonate (VC), diethylcarbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC),methyl formate (MF), γ-butyrolactone (γ-BL), sulfolane, methyl acetate(MA) or methyl propionate (MP); a gel polymer electrolyte using PEO,PVdF, PVdF-HEP, PMMA, PAN, or PVAc; and a solid electrolyte using PEO,polypropylene oxide (PPO), polyether imine (PEI), polyethylene sulphide(PES), or polyvinyl acetate (PVAc).
 12. The cable-type secondary batteryaccording to claim 1, wherein the electrolyte further comprises alithium salt.
 13. The cable-type secondary battery according to claim12, wherein the lithium salt is selected from the group consisting ofLiCl, LiBr, LiI, LiClO₄, LiBF₄, LiB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃, LiCF₃CO₂,LiAsF₆, LiSbF₆, LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li, (CF₃SO₂)₂NLi, lithiumchloroborate, lower aliphatic lithium carbonate, lithiumtetraphenylborate, and mixtures thereof.
 14. The cable-type secondarybattery according to claim 1, wherein the inner electrode is an anodeand the outer electrode is a cathode, or the inner electrode is acathode and the outer electrode is an anode.
 15. The cable-typesecondary battery according to claim 1, wherein when the inner electrodeis an anode and the outer electrode is a cathode, the inner electrodeactive material layer comprises an active material selected from thegroup consisting of natural graphite, artificial graphite, orcarbonaceous material; lithium-titanium complex oxide (LTO), and metals(Me) including Si, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe; alloys of themetals; oxides (MeOx) of the metals; complexes of the metals and carbon;and mixtures thereof, and the outer electrode active material layercomprises an active material selected from the group consisting ofLiCoO₂, LiNiO₂, LiMn₂O₄, LiCoPO₄, LiFePO₄, LiNiMnCoO₂,LiNi_(1-x-y-z)Co_(x)M1_(y)M2_(z)O₂ (wherein M1 and M2 are eachindependently selected from the group consisting of Al, Ni, Co, Fe, Mn,V, Cr, Ti, W, Ta, Mg and Mo, and x, y and z are each independently anatomic fraction of oxide-forming elements, in which 0≦x<0.5, 0≦y<0.5,0≦z<0.5, and x+y+z≦1), and mixtures thereof.
 16. The cable-typesecondary battery according to claim 1, wherein theelectrolyte-absorbing layer comprises a polymer selected from a gelpolymer electrolyte using PEO, PVdF, PVdF-HFP, PMMA, PAN, or PVAc; and asolid electrolyte using PEO, polypropylene oxide (PPO), polyether imine(PEI), polyethylene sulphide (PES), or polyvinyl acetate (PVAc).
 17. Thecable-type secondary battery according to claim 1, wherein theelectrolyte-absorbing layer further comprises a lithium salt.
 18. Thecable-type secondary battery according to claim 17, wherein the lithiumsalt is selected from the group consisting of LiCl, LiBr, LiI, LiClO₄,LiBF₄, LiB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃, LiCF₃CO₂, LiAsF₆, LiSbF₆, LiAlCl₄,CH₃SO₃Li, CF₃SO₃Li, (CF₃SO₂)₂NLi, lithium chloroborate, lower aliphaticlithium carbonate, lithium tetraphenylborate, and mixtures thereof. 19.The cable-type secondary battery according to claim 1, wherein when theinner electrode is a cathode and the outer electrode is an anode, theinner electrode active material layer comprises an active materialselected from the group consisting of LiCoO₂, LiNiO₂, LiMn₂O₄, LiCoPO₄,LiFePO₄, LiNiMnCoO₂, LiNi_(1-x-y-z)Co_(x)M1_(y)M2_(z)O₂ (wherein M1 andM2 are each independently selected from the group consisting of Al, Ni,Co, Fe, Mn, V, Cr, Ti, W, Ta, Mg and Mo, and x, y and z are eachindependently an atomic fraction of oxide-forming elements, in which0≦x<0.5, 0≦y<0.5, 0≦z<0.5, and x+y+z≦1), and mixtures thereof, and theouter electrode active material layer comprises an active materialselected from the group consisting of natural graphite, artificialgraphite, or carbonaceous material; lithium-titanium complex oxide(LTO), and metals (Me) including Si, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe;alloys of the metals; oxides (MeOx) of the metals; complexes of themetals and carbon; and mixtures thereof.
 20. The cable-type secondarybattery according to claim 1, wherein the separation layer is anelectrolyte layer or a separator.
 21. The cable-type secondary batteryaccording to claim 20, wherein the electrolyte layer comprises anelectrolyte selected from a gel polymer electrolyte using PEO, PVdF,PVdF-HFP, PMMA, PAN, or PVAc; and a solid electrolyte using PEO,polypropylene oxide (PPO), polyether imine (PEI), polyethylene sulphide(PES), or polyvinyl acetate (PVAc).
 22. The cable-type secondary batteryaccording to claim 20, wherein the electrolyte layer further comprises alithium salt.
 23. The cable-type secondary battery according to claim22, wherein the lithium salt is selected from the group consisting ofLiCl, LiBr, LiI, LiClO₄, LiBF₄, LiB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃, LiCF₃CO₂,LiAsF₆, LiSbF₆, LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li, (CF₃SO₂)₂NLi, lithiumchloroborate, lower aliphatic lithium carbonate, lithiumtetraphenylborate, and mixtures thereof.
 24. The cable-type secondarybattery according to claim 20, wherein the separator is a poroussubstrate made of a polyolefin-based polymer selected from the groupconsisting of ethylene homopolymers, propylene homopolymers,ethylene-butene copolymers, ethylene-hexene copolymers, andethylene-methacrylate copolymers; a porous substrate made of a polymerselected from the group consisting of polyesters, polyacetals,polyamides, polycarbonates, polyimides, polyether ether ketones,polyether sulfones, polyphenylene oxides, polyphenylene sulfides andpolyethylene naphthalenes; or a porous substrate made of a mixture ofinorganic particles and a binder polymer.
 25. A cable-type secondarybattery having a horizontal cross section of a predetermined shape andextending longitudinally, comprising: two or more cores for supplyinglithium ions, which comprises an electrolyte; two or more innerelectrodes arranged in parallel to each other, each inner electrodecomprising an open-structured inner current collector surrounding theouter surface of each core for supplying lithium ions, an innerelectrode active material layer formed on the surface of the innercurrent collector, and an electrolyte-absorbing layer formed on theouter surface of the inner electrode active material layer; a separationlayer surrounding the outer surface of the inner electrode to prevent ashort circuit between electrodes; and an outer electrode surrounding theouter surface of the separation layer and comprising an outer electrodeactive material layer and an outer current collector.
 26. A cable-typesecondary battery having a horizontal cross section of a predeterminedshape and extending longitudinally, comprising: two or more cores forsupplying lithium ions, which comprises an electrolyte; two or moreinner electrodes arranged in parallel to each other, each innerelectrode comprising an open-structured inner current collectorsurrounding the outer surface of each core for supplying lithium ions,an inner electrode active material layer formed on the surface of theinner current collector, and an electrolyte-absorbing layer formed onthe outer surface of the inner electrode active material layer; and anouter electrode surrounding the outer surface of the inner electrode andcomprising an outer electrode active material layer and an outer currentcollector.